The use of flour produced through the processing of cereal grains such as wheat, rye, and oats is an important feature in nutrition and food production around the world. Grains are grown, harvested, and milled into flours, which are used to make breads, bakery products, pastas, all of which are staples in the diet of many individuals world wide. Grains and grain products are also utilized for brewing and fermentation.
Wheat flour is an important ingredient in home baking and is the foundation for almost every commercially baked product and pasta. Of the grains available for the production of flour, wheat is unique in that it is the only cereal grain with sufficient gluten content to make a loaf of bread without being mixed with another grain. Wheat is grown all over the world and is the most widely distributed cereal grain. In general, a reference to “flour” is a reference to wheat flour. Flour is used extensively in the food industry and a key requirement in that industry is the uniform high quality and performance of flour and grains in food and beverage production (For review see: Plant Foods for Human Nutrition, Vol 55:1–86, 2000).
Cereal grains store energy as starch, and to perform well in baking and food production, it is important to optimize the level of starch in flour. A key factor in the breakdown of starch in flours is the presence of α-amylase activity in cereal grain flours. α-amylase is an endoenzyme that is present in cereal grains and breaks the α-1,4, glucosidic bonds that are present in starch. The enzyme works in an almost random manner and the effect of its enzymatic activity is the breakdown in the size of the starch molecules and the conversion of starch to sugar.
To help ensure efficient food production methods, it is important to be able to accurately assess the level of α-amylase activity in batches of flour. The presence of excess α-amylase activity flour results in a reduction in the value of the flour for baking. For example, excess starch breakdown in flour can result in sticky or doughy bread that can't be cut in automated loaf-slicing machinery and is therefore unsuitable for commercial production. Insufficient α-amylase activity in flour can also reduce the value of a flour for baking and food production. Insufficient α-amylase activity in flour can result flour that lacks the necessary levels of sugars for proper fermentation and yeast activity in baking. Because of the financial importance of flour quality in the baking and food production industries, it is important to have reliable, reproducible, and easy-to-use methods to determine the amount of α-amylase activity in flours.
Current methods to determine the level of α-amylase in flour include techniques such as the Hagberg-Perten Falling Number test. This is a viscosity-based method in which a flour suspension is heated to gelatinize the starch. The viscosity of the mixture is determined by putting the suspension into a long narrow tube of defined dimensions and measuring the rate at which various calibrated small stirrers or a rod falls though the suspension in the tube. Although the Falling Number test is currently accepted as the industry standard, it does not measure the actual α-amylase enzyme activity level directly, and it is the activity of the enzyme that affects baked good texture and value.
Alternative methods that directly measure α-amylase enzyme activity have been developed, but are not used to directly test flour or stock samples, which limits their usefulness. The availability of a method to directly determine α-amylase enzyme activity in flour or stock samples would provide a more accurate prediction of a flour's or stock's performance, and therefore its value in the baking industry and in other food and beverage production industries.